Electrostatic recording apparatus with core matrix

ABSTRACT

Selecting pulse signals for selecting recording positions are combined with input information such as picture signals to produce the recording signals representing not only the optical density of recording but the recording positions, and the recording signals are converted into the driving signals which are applied to selected input terminals of a transfomer assembly so that across the series-connected secondary windings corresponding to the recording position indicated by the selecting pulse signal there is induced the electrostatic recording voltage. The recording voltages are applied to recording electrodes or styluses to form an electrostatic latent image of said input information upon a recording medium. The latent image is developed and fixed to provide a permanent recording.

United States Patent 1191 Kondo 'et a1.

[ ELECTROSTATIC RECORDING APPARATUS WITH CORE MATRIX [75] Inventors: Mamoru Kondo; Morio Kobayashi,

both of Mito, Japan [73] Assignee: Nippon Telegraph and Telephone Public Corporation, Tokyo. Japan 22 Filed: Aug. 13, 1973 21 Appl. No.: 387,596

[30] Foreign Application Priority Data l TRANSFORMER ASSEMBLY Mar. 11, 1975 12/1971 Monnier 346/74 ES 3,732,573 5/1973 Merka 346/74 ES Primary Examiner-Bernard Konick Assistant Examiner-Jay P. Lucas [57] ABSTRACT Selecting pulse signals for selecting recording positions are combined with input information such as picture signals to produce the recording signals representing not only the optical density of recording but the recording positions, and the recording signals are converted into the driving signals which are applied to selected input terminals of a transfomer assembly so that across the series-connected secondary windings corresponding to the recording position indicated by the selecting pulse signal there is induced the electrostatic recording voltage. The recording voltages are applied to recording electrodes or styluses to form an electrostatic latent image of said input information upon a recording medium. The latent image is developed and fixed to provide a permanent recording.

18 Claims, 22 Drawing Figures I I I I I I I I FIG.

IA FIG.

FIG.

SHEET 01 0F 12 AMPLIFIER AMPLIFER AMPLIFER llllIuLlIIIlIl- IIIIII- MONOSTABLE MULTIVIBRATOR FLOP I, FLIP- CLOCK PULSE GENERATOR PATENTED MARI 1 I975 SHEET 03 0F 1'2 E: 23 v Q3 m: 0:4 moj mo] N03 $03 no; vol moi mo: 6:

@E ME WE ME NE 0 E E $.E E mu E E N OI.

PATENTEB HART I I975 3.871.003 SHEET CMUF 12 LL E52 mo LlJLlJ ac:

E 0 I F-E a o O Na POSITIVE POLARITY SUITABLE SUITABLE l RECORDING RECORDING VOLTAGE VOLTAGE F| F2 FIG EH EI T2 5 20 H2] C Q Esw- H C d E:' H4O@ C Q E41 H41 T5 E H 5 Ha O O Esl H6| PATENTEBHARI 1 I975 FIG.

r m C C m 6 1 O 23 O 23 @mwwmv WWWW @MM MU W $333 3333 3333 Li ti ii @555 @@Q@ BFJQB PATENTEDHARI 1 1975 SHEET CSUF 12 FIG. 7B

DRIVE TRANSFORMER L PATENTED I 3.871.003 SHEET 110F12 FIG.

lll -lll FIG. I 2

FIG. I 3

ELECTROSTATIC RECORDING APPARATUS WITH CORE MATRIX BACKGROUND OF THE INVENTION The present invention relates to generally an electrostatic recording. apparatus and more particularly a high-speed electrostatic recording apparatus of the type recording input information with the electrostatic recording voltages induced and applied to recording electrodes or styluses selected by recording position selecting pulses.

In general, the recording speed of most of recording apparatus for recording information transmitted by a data transmission line or processed by an electronic computer is very low as compared with the data transmission line or data processing speed so that a highspeed recording apparatus has been demanded. Furthermore a recording apparatus which produces less or no recording noise has been demanded. Therefore, research and development of various non-impact recording systems such as electrostatic recording systems, electrophotographic recording systems, silver halide recording systems, heat-sensitive recording systems, dry silver recording systems, ink jet recording systems and so on have been carried out. Of these non-impact recording systems, the electrostatic recording systems are most advantageous because the recording speed is high, the recorded images have good qualities, the power consumption is less and the apparatus itself is simple in mechanism. The electrostatic recording systems have been widely used in the fields of dot matrix electrostatic printers, plotters, facsimile systems and so on. In view of economy and recording density however, the conventional electrostatic recording apparatus has not been satisfactory mainly because of the problem of distributing the electrostatic recording voltages among recording electrodes or styluses. One typical example of the conventional electrostatic recording apparatus generally comprises an AND gate circuit, amplifiers, transformers and a recording electrode or stylus head. A plurality of AND gates are sequentially opened to pass the picture signals to the amplifiers, and the outputs of the amplifiers are applied to a primary winding of a pulse transformer so that a high voltage may be induced across the secondary winding thereof and supplied to a multistylus electrode. An electrostatic latent image is formed upon a recording medium in contact with the multistylus electrode, and developed and fixed to produce the permanent recording. The multistylus electrode of the electrostatic apparatus of the type described has 1,275 styluses with a stylus density of I50 styluses per inch in order to reproduce or record a satisfactory image upon a recording medium with the width of 8 /2 inches so that 1,275 amplifiers and 1,275 pulse transformers are required. As a result, the conventional electrostatic recording apparatus of the type described is extremely large in size and very expensive.

SUMMARY OF THE INVENTION In view of the above, the primary object of the present invention is to provide a high-speed electrostatic recording apparatus based upon the novel electrostatic recording voltage distribution method so that printing or recording with a high recording density can be accomplished at such a high speed as compatible with the datatransmission speed or data processing speed.

Another object of the present invention is to reduce the numbers of amplifiers and pulse transformers based upon the novel electrostatic recording voltage distribution method so that an electrostatic recording apparatus which is compact in size, light in weight and inexpensitive to manufacture may be provided. V

A further object of the present invention is to provide an electrostatic recording apparatus capable of highspeed recording with a high recording density based upon the novel electrostatic recording voltage distribution method.

The above and other objects, features and advantages of the present invention will become more apparent from the following description of the preferred embodiments thereof taken in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING:

FIG. 1 (consisting of FIGS 1A and 1B) is a block diagram of a first embodiment of the present invention;

FIG. 2 is a simplified diagram illustrating the relation between the primary windings and the secondary windings of a transformer assembly of the first embodiment shown in FIG. 1;

FIG. 3 is a graph illustrating the electrostatic recording voltage vs. optical density of recording characteristic curves of a recording medium;

FIG. 4 is a simplified diagram illustrating the arrangement of the primary and secondary windings of a transformer assembly of the type which can respond to the unipolar input;

FIG. 5 (consisting of FIGS 5A and 5B) is a block diagram ofa second embodiment of the present invention;

FIG. 6 shows diagrammatically the arrangement of the transformer assembly of the type in which the output terminals are selected one by one;

FIG. 7 (consisting of FIGS 7A and 7B) is a block diagram ofa sixth embodiment of the present invention of the type in which the electrostatic recording voltages are simultaneously applied to a plurality of recording styluses;

FIGS. 8-10 show diagrammatically the arrangements of the transformer assemblies of the type capable of simultaneously outputting the electrostatic recording voltages from a plurality of output terminals thereof;

FIGS. 11-15 are cross sectional views of bobbins of the transformer assemblies illustrating the arrangements of the secondary windings in accordance with the present invention; and

FIG. 16 is a diagram of a fourteenth embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS:

First Embodiment Referring to FIG. 1 illustrating diagrammatically an electrostatic recording apparatus in accordance with the present invention, a picture signal is applied to a picture signal input terminal 11. The output signals of a selecting pulse generator 12 are applied to a gate circuit 13, and the signals which pass through the gate circuit 13 are amplified by a driver 14 and applied to primaries Il -H of a transformer assembly 15 through terminals E E In the transformer assembly 15, secondaries I -L are wound on a core T in the same direction as that of the primary H Secondaries Lgo -Lgog are wound on a core T in a direction the same that of the primary H whereas the secondaries L -L are in the opposite direction. On -a core T are wound secondaries L L and L -L in a direction the same as that of the primary H whereas secondaries L L and .Lm-L are in the opposite direction. On a core T are Wound secondaries L401, L402, L405, L405, L409, L4 0,

L and L in a direction the same as that of the pri- 1 2 a 5 0 a a F 12 F13 11 15 m T, +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 T +1 +1 +1 +1 +1 +1 +1 +1 -1 1 1 1 1 1 1 1 T, +1' +1 +1 +1 1 1 1 1 +1 +1 +1 +1. -1 1 1 1 1 T, +1 +1 -1 -1 +1 +1 1 1 +1 +1 +1 1 +1 +1 -1 1 T, +1 1 +1 1 +1 1 +1 1 +1 1 +1 1 +1 1 +1 1 T, +1 1 +1 1 1 +1 +1 1 +1 1 1 +1 mary H whereas secondaries L L L L L L L and L are in the opposite direction. On a core T are wound secondaries L L L L 1509, L511, L513 1.4515 in a directlOn the same 85 of the primary H whereas secondaries L L L L508, L510, L512, L5 and L516, are in the Opposite direC- tion. On a core T are wound secondaries L L L606, L307, L810, LgufLg a and L616 in the direction the same as that of the primary H whereas secondaries L602: eos aos aos L609, L612, L614 and L615, are in the opposite direction.

The same voltage V, is impressed across the primary windings Fifi-I and the secondary voltages having the same absolute value are induced across the secondaries, but the voltages +V induced across the secondaries wound in the direction the same as that of the primariesH -H have the same polarity as that of the voltages impressed across the primaries whereas the voltages V induced across the secondaries wound in the opposite direction with that of the primaries have the oppositepolarity. t V

One end of the secondary-L is connected to a terminal F whereas the other end, to the secondary L which in turnis connected in series to the secondaries L L L and L which are connected in series.

The other end of the secondary L is grounded. These. 45

six secondary windings on the six cores connected in series comprise a selecting line of the terminal F The SGCOHdaIiBS L102, L202, L302, L402, L502 and L602 are connected in series and one end of the secondary L is connected to a terminal F whereas the secondary L is grounded. In like manner, the secondaries L -L LIN-L604, 105 605a ies- 606, LIN-L607, L108 L608 roa eas .LHW'LGIO l11 6l1 uzs12 uz- 613, LIN-L514, L n-L 5 and-L "-L are all Conrlcted in series, respectively, and the secondaries Lung-L11 are connected to terminals F F respectively, whereas the secondaries L -L are grounded. The terminals F F are connected to styluses of a multistylus electtss gsirssas i x lr- When the voltages are applied to the multistylus electrode 16, the electrostatic latent images are formed upon a recording medium 17. The latent images are developed and fixed to provide the permanent recording. Alternatively, the latent images may be developed upon the recording medium and then transferred upon a recording paper. In this case the recording medium may beused repetitively. Furthermore, the latent im;

20 where +1 +V and -l -V In the winding matrix, each column corresponds to each selecting line. When the driving voltage pulses of +V are simultaneously impressed to the input terminals E -E the voltages V with the polarities depending upon the direction of the secondaries areinduced across the secondaries L -L respectively. As a result the voltage at the output terminal F is the sum of the voltages induced across the secondaries L L L301, L401, L501 and L601, lS +6V2, the Voltages at the output terminals F P become +2V +2V +2V +2V +2V +2V 2V +2V +2V +2V 2V +2V 2V -2V and 2v respectively. The relatively high voltage +6V at the'output terminal F will be referred to as the selected output voltage whereas the relatively small voltages :ZV, at the output terminals FzFw, as the spurious output" hereinafter in this specification. When the driving voltages +V,, +V +V +V V and V, (which correspond the elements of the second column of the winding matrix, Table l) are applied to the input terminals I -F respectively, the selected output of +6V appears at the output terminal F In like manner, when the drive voltage pulses corresponding to the elements of a selected column of the winding matrix are applied to the input terminals E E the selected output +6V appears at a corresponding or selected output terminal, whereas the spurious output voltages appear at the other output terminals. The ratio of the absolute value of the spurious output (-2V or +2V to that of the selected output is called the selecting ratio which is one-third in the instant embodiment.

The transformer asembly 15 is illustrated in a simplified form in FIG. 2. The secondaries across which are induced the secondary voltages with the same polarity with that of the primary voltage are indicated by opened windings whereas the secondary windings across which are induced the secondary voltages with the polarity opposite to that of the primary voltage are indicated by twisted or/closed windings. The winding matrix of the transformer assembly may be obtained from the (n,k) error-correcting code. For example from Golay code is obtained a winding matrix with 24 inputs, 2048 outputs and a selecting ratio of one-third.

FIG. 3 shows the relation between the electrostatic recording voltage applied recording styluses and the optical density of an image recorded upon a recording medium. In general, this relation changes depending upon the size of a recording stylus, the type of a recording medium, and the polarity of recording voltage, but the relation may be generally depicted as shown in FIG. 3. It is seen that no recording is made with a voltage between the upper threshold voltage V (about +400 V) and the lower threshold voltage V,, (about 400 V) and that the recording may be effected with a suitable recording voltage higher than the upper threshold voltage V or lower than the lower threshold voltage V,,. When the selected output +6V is used for the electrostatic recording voltage which is higher than the upper threshold voltage +400V, only the selected stylus makes a recording but the other styluses will not make a recording because the spurious voltage is much less than +6V In other words, the spurious voltage is so selected as to' fall in the range between the upper and lower threshold voltages V, and, V whereas the selected output voltage, is selected as to be higher than the higher threshold voltage V or lower than the lower threshold voltage, V,,.

Referring back to FIG. 1, the control unit comprising the selecting pulse signal generator 12 and the gate circuit 13 will be described hereinafter. The selecting pulse signal generator, 12 is adapted to generate the pulse signals for selecting the styluses of the multistylus electrode 16. That is, the generator 12 outputs the signals corresponding to the elements of the columns 1-16 of the winding matrix shown in Table I. In practice, however, the generator 12 outputs the signal 0 when the element is +1 and the signal l when the element is -l.

Flip-flops 211, 212, 213 and 214 of a binary counter 21 give the outputs a a a and a., which correspond to the elements of the second, third, fourth and fifth rows of the winding matrix shown in Table l. The output a which corresponds to the element of the sixth row of the winding matrix is obtained by a eB a qaafia this logic operation being performed by exclusive OR circuits 221, 222 and 223. Since the elements of the first .row are all ls, no logic circuit for giving the signal 0 is provided.

Next the mode of operation of the control unit including the driver 14 will be described hereinafter. First all of the flip-flops 211-214 of the binary counter 21 are set to the state 1, and in response to the clock pulses transmitted from a clock pulse generator 20, the output signals 1 and 0 corresponding to the elements of the columns of the winding matrix are fed into-the gate circuit 13 comprising AND gates 241+-246+ and 242-246- and NOT circuits 231-235. Only one of each pair of AND gates 242' and 242 246+ and 246- is opened by the signal from the selecting signal generator 12. To the AND gates 241-246 are applied the picture signals in synchronism with the clock pulses and the pulses from a monstable multivibrator 25 which determines the width of pulses fed to the transformer assembly 15 through driver 14. For instance, when the output a, from flip-flop 211 in the signal generator 12 is 0, a pulse of which height is determined by the picture signal and of which width is determined by the pulse from the monostable multivibrator 25 is fed to an amplifier 142 in the driver 14 through the AND gate 242+. On the contrary, when the output a is l, the pulse is fed to the amplifier 142 through the AND gate 242. The amplifiers 142-146 of the driver 14 are of the bipolar type and give the voltage signal +V, to the terminals E -E when the pulse signal is fed from AND gates 242+-246+ and give the voltage signal -V to the terminals E -E when the pulse signal is fed from AND gates 242-246. The amplifier 141 gives the output signal +V of which height is determined by the picture signal to the input terminal E of the transformer assembly 15. Thus, the selected output the magnitude of which is dependent upon the magnitude of the pciture signal appears at the output terminal F in the sequence determined by the winding matrix Table l. The styluses of the multistylus electrode 16 are energized to form an electrostatic latent image upon the recording medium.

The pulse width, which is determined by the monostable multivibrator 25, must be so selected as to satisfy the following conditions:

1. the pusle width or duration must be longer than the pulse width of about 0.1 p. sec. required for electrostatic recording. I

2. the pulse width must be short so that the cores of the transformer assembly 15 are not saturated so as to avoid distortion of the output voltage.

3. the interference between the adjacent pulses must not distort the output voltage waveforms of the transformer assembly.

In the instant embodiment, bipolar amplifiers 141-146 are used because the bipolar output voltages must be applied to the input terminals E -E but they are generally complex in construction so that a transformer assembly 15 in which the positive and negative voltages can be induced across the secondary windings in response to a unipolar primary voltage may be used as will be described in detail hereinafter with reference to FIG. 4.

Referring to FIG. 4, the primary windings H H H H H and H are wound on the cores T -T respectively, in the same direction as the primary windings in FIG. 1 whereas the primary windings H H H H H and H are wound in the opposite direction. One end of each of the primaries H and H are connected together and are grounded whereas the other ends are connected to input terminals E and E respectively. In like manner, one end of each of the primaries H and H H and H H and H H and H and H and H are connected together respectively and grounded whereas the other ends are connected to the input terminals E E E E E E E E E and E respectively. When the input voltages are applied to the input terminals E E E E E and E the output terminal F is selected, that is the selected output voltage appears at the output terminal F When the input voltages are applied to the input terminals E E E E E and E the selected output voltage appears at the output terminal F since the primaries H and H are wound i n the direction opposite to that of the other primaries H -H Second Embodiment In the electrostatic recording system utilizing a multistylus electrode in which fine styluses are put closely to give fine picture, the electrical insulation layer between the adjacent styluses is very thin (for example less than 0.1 mm) and the high electrostatic recording voltages (for example higher than 600V) are applied to the styluses so that the electrical insulation between the adjacent styluses tends to be frequently broken and the discharge occurs between the adjacent styluses. As a result, the quality of the recorded image becomes very poor and unsatisfactory and ins some cases the styluses are severely damaged. Furthermore, it is not preferable from an economical view point that the potential difference between the adjacent styluses becomes too high because of the increase in power consumption and also because the ineffective energy consumed due to the stray capacitance between the adjacent styluses is in proportion to the square of the potential difference be tween the adjacent styluses. It is therefore preferable to minimize the potential difference between the adjacent styluses by utilizing the spurious outputs of the transformer assembly. For this purpose, the winding matrix shown in Table 2 is used.

The winding matrix shown in Table 2 is an improvement of the winding matrix shown in Table 1. 1n the transformer assmebly based upon the winding matrix shown in Table 2, the voltage difference between the adjacent output terminals is 4V at the most whereas the voltage difference in the transformer assembly of the first embodiment is 8V When the elements of the two columns of the matrix shown in Table 2 are compared, it is seen that two elements are always different from each other. For example the elements of the first and second columns are different from each other in the 5th and 6th rows.

The matrix shown in Table 2 is obtained by rewriting the matrix shown in Table 1. That is, the columns of the matrix shown in Table l are re-arrayed in the order of the 1st, 2nd, 4th, 3rd, 7th, 8th, 6th, 5th, 13th, 14th, 16th, th, 10th, 12th, 11th and 9th. In summary, the columns of one winding matrix may rewritten or rearrayed so that the number of elements in the corresponding rows different from each other in two adjacent selected columns may be minimized. Alternatively, such a winding matrix may be formed independently and a transformer assembly may be constructed based upon this winding matrix so that the voltage difference between the adjacent output terminals may be minimized. It is a mathematical problem to obtain a winding matrix of the type described above.

Next referring to FIG. 5 illustrating diagrammatically 50 the second embodiment of the present invention, the

transformer assembly has k input terminals and 2" output terminals. When one output terminal is assigned a number j, then j l is a positive integer from 0 to 2" l and is given in the binary system j--l==a a .a Ha,

where a 1 or O at the i-th digit position from the most significant digit.

Next from the following equations u n u n i1.1

(i=2,3,...k) 5 CU t1 1 (i=l,2,...k)

b is calculated. The results when k 4 are shown in T5 2 33- When the transformer assembly is constructed based upon a winding matrix shown in Table 4 in which 0,,- is 'an element of the ith row and j-th column, the selected output voltage is kV whereas the voltage difference between the adjacent output terminals is 2V b,-,- is known as Gray code in which the digits of the consecutive numbers are the same inevery place except one, I and in that place the digitsdiffer by one unit. c is the code in which when b is 0, it is replaced by +1 whereas when b is 1, it is replaced by 1. The winding matrix shown in Table 4 is obtained by arraying the rows of the column c in Table 3 as the columns and the columns as the rows.

a b c J 1' n "2: .11 "4.! u 2: a: u C ii 11 C31 Q1 1 0 0 0 O O 0 0 0 0 1 1 1 l 2 1 0 O O 1 0 O O l 1 l 1 1 3 2 0 0 1 0 O 0 1 1 l 1 -1 1 4 3 0 0 1 1 0 0 1 0 l l l 1 5 4 0 1 0 O O 1 1 0 1 1 -l l 6 5 0 l O 1 O l 1 l 1 1 1 1 7 6 O l l O 0 l 0 1 l 1 1 1 8 7 0 1 1 1 0 1 0 O l *1 1 1 9 8 1 0 0 0 l l 0 0 1 1 l 1 1O 9 1 0 0 1 1 l 0 1 l 1 1 -1 11 1O 1 0 1 0 1 1 1 1 1 l 1 1 12 1 1 1 0 1 1 1 1 1 (l 1 l -1 l 13 12 1 1 0 O 1 0 1 0 1 l l 1 14 13 1 1 0 1 1 O 1 1 l 1 l 1 15 14 l l 1 0 l O 0 1 -1 1 1 1 16 15 1 1 1 1 1 0 0 0 1 1 1 1 Table 3 Fourth Embodiment Next, the fourth embodiment in which the transformer assembly has n input terminals and 2" output terminals (k positive integers less than n), will be described. The transformer assembly is constructed based upon the (n,k) error-correcting code so that the voltage difference between the adjacent output terminals may be minimized.

First, the simplest example where n 4 and k 3 will be described. In this case, the (4,3) code may be utilized. When one output terminal is assigned a number j, then (j-l) is a positive number from to 2"l which is expressed in the binary system as follows:

Since k 3, the right term is a a a a 11 a a. a @a ba is called (4,3) code, which is shown in Table 5, column a. It is seen that any two elements are different from each other when two rows are compared with each other. In the error-correcting code, the number of digits positions in which the corresponding digits of two binary numbers of the same length are different is called a Hamming distance" or a distance. The minimum of distance is called the minimum distance." In the (4,3) code, the distance is greater than 2 so that the minimum distance is 2. Ofthe bits a a a and a. of (4,3) code, three bits a a and a in the form of binary number system are called the information bits whereas a. obtained by the calculation of the difference between the adjacent output terminals becomes minimum.

In practice, in the transfer assembly based upon the (4,3) code described above, the spurious output becomes 4, but it may be increased by i2 by superimposing a constant bias voltage so that the selecting ratio of 1/3 may be obtained when the selected output is 6.

So far, Gray code is used in order to improve the (n,k) code so as to have the minimum distance between adjacent code words, but it does not follow that Gray code is always used. The following codes may be utilized in the present invention.

1. A code in which the parity check is made by additional bits and which is generally represented by (k 1,k) code. An example is (4,3) code described hereinbefore.

2. The so-called orthogonal array code.

3. (12,7) code represented by e 11 21 an '11 G3 31 e u 69 31 1 aj Q by Q 1751 and [7 1$ be, [37 The bits b b and b are not used though they are information bits. This code is an improvement of SASAKI code. In addition, SASAKI code, Golay codes such as (18,9) code, and (24,12) code may be utilized.

Fifth Embodiment In the fifth embodiment, the unipolar pulses are applied to the input terminals E +E of the transformer assembly 15 in which two secondary windings are connected. Referring to FIG. 6, the primary windings wound on the cores "f -T in the same direction are connected to the input terminals E,+E respectively, and four secondary windings are wound on each of the cores T,+T in the same direction. The winding matrix information bits is called a check bit. of this transformer assembly 15 is shown in Table 6.

a b c n "21 a; n u u 3! u u C21 11) C41 (4,3) code shown in column b of Table 5 is used to construct a transformer assembly in which the voltage F, F, F, F, F, F, F, F, F, F... difference between the adjacent output terminals be- 0 0 O 0 l I 0 comes minimum. The information bits b b and b i I O 0 0 0 O I corresponding to the bits a a and a are given by uti- T, 0 1 1 0 1 1 0 0 0 0 T 0 0 0 1 1 0 1 1 0 0 112mg Gray code by O 0 0 O O k 0 I l u n 21 2J 11U= ar 31 21- and In Table 6, 1 represents the secondary winding while 41 u 21 11; 0 represents no secondary winding. The secondary In the improved (4,3) code, the distance between any two adjacent code words is 2.

Next, based upon the following equation C =2b l (i= 1,2, 3 and 4; andj= 1, 2,

and 8) Os in the column b of Table 4 are replaced by Is whereas l s by -ls so that the code shown in column c in Table 4 is obtained. In the transfer assembly constructed based upon the code in column C, the voltage windings of the columns are connected in series. For instance, two ls in the first column of the winding matrix represent the secondary windings wound on the cores T and T are connected to the output terminal F, in series. The feature of the winding matrix shown in Table 6 is that when two columns are compared with each other, there are always two different elements. A further feature is that two elements of each column are always ls whereas three elements are always 0s $ince plete block designs. Steiner system which is repre sented by S(t,k,v) is known as a set of arrangements out of v-objects into blocks of k objects'in which the block that contans any combination oft objects is found only once. The element n,-,- of the combination matrix representing the above arrangement is I when the i-th object is contained in thej-th block, but when the i-th object is not contained in the j-th block. In order to construct the transformer assembly based upon this matrix, the input terminals are represented by the objects whereas the output terminals are represented by the blocks and the combination matrix is used as the winding matrix. Then, the number of input terminals equals v, the weight is k, the selecting ratio is (t 1 )/k, and the maximum number of output terminals is ,C,/ C,, where C is the symbol of combination.

For example, Mathieu code is S(5,8,24) so that the number of input terminals is 24, the weight is 8, the selecting ratio is 4/8 and the maximum number of output terminals is 759.

The advantage of the fixed weight error-correcting code resides in the fact that the unipolar driving pulses may be used so that the driving circuit maybe made simple in construction. In the transformer assembly constructed based upon the combination matrix the output terminals are selected one by one.

Sixth Embodiment Next referring to FIG. 7, the sixth embodiment of the present invention will be described hereinafter. The facsimile receiver shown in FIG. 7 is of the type capable of recording simultaneously three picture elements. In the'control unit 25, the serial picture signals applied to the input terminal 11 are converted into three parallel picture signals which are applied to amplifiers 261, 262 and 263 in the driver 26. The outputs of the amplifiers 261,262 and 263 are applied to the input terminals E E and E of the transformer assembly 27. In order to designate the recording positions of the first three picture signals, the recording position selecting signal is applied to the amplifier 264 so that the driving pulse or the output of the amplifier 264 may be applied to the input terminal E of the transformer assembly 27 which is constructed based upon a winding matrix shown in Table 7.

features of the winding matrix shown in Table 7 are that when two columns are compared, two elements differ and that each column has always two ls. Since the weights of all of the rows are 2 in the matrix shown in Table 7, the matrix is a fixed weight error correcting code. When the input voltages +V are applied to the input terminals B -E and the input voltage +V, is simultaneously applied to the input terminal E the selected output voltage +2V is induced across the series connected secondary windings corresponding to the first, second and third rows of the winding matrix shown in Table 7, but the spurious outputs 0 or +V appear at the other output terminals F ,-F and F ,-F When the input voltage is applied to input terminal E (where i= 1, 2 and 3) and to one of the input terminals E E or E to two of them or all of them, the selected output voltage +2V appears at one of the three output terminals F F and F,-;,, at two of them or all of them. The selecting ratio is 1/2. As with the case of the other embodiments of the present invention, the level of the spurious output is so selected that no electrostatic recording will be made.

In response to the clock pulses supplied from the clock pulse generator 28, the picture signals applied to the input terminal 11 are sequentially transferred into a shift register 29, and when three picture signals are transferred into the shift register 29, a counter 30 gives the output signal to AND gates 31 so that the contents of the shift register 29 are simultaneously transferred in parallel through the gates 31 into a buffer register 32. The counter 30 also gives the output signal which has been reset. As a result, a flip-flop 341 changes to the state 1 whereas other flip-flops 342 and 343, to the state 0. The output signal of the counter 30 is transmitted also to a monostable multivibrator 35 which gives to AND gates 33 pulse signals with a suitable pulse duration so that the three picture signals stored in the buffer register 32 are transferred in parallel to the amplifiers 261, 262, and 263 in the driver 26, and the record ing position designating signals are transferred into the driver 26 from the shift register 34. These signals are amplified and applied to the transfer assembly 27 so that the selected output voltages appear at the output terminals F F and F depending upon the picture signals. As a result, three dots are simultaneously re In Table 7, the element 1 represents that the secondary windings are wound on the cores T -T and T -T whereas the element 0 represents that'no winding is corded by styluses 35 on the recording medium 37.

As soon as the contents of the shift register 29 are transferred into the buffer register 32, the next three picture signals are stored one by one in the shift register 29. In like manner, the next three dots are recorded. The above operations are cycled until the desired electrostatic recording is obtained.

In order to improve the selecting ratio, between the ground and the junction G, between the primary winding H 5 and a common lead wire there may be inserted a primary winding wound upon a core whose secondary may be minimized. That is, in the matrix shown in Table 8 the elements of the adjacent columns are different in only two rows. Anothr improvement of the matrix shown in Table 7 is shown in Table 9.

To explain this winding matrix, the output terminals are represented by F (i= 1, 2, and 3;j= l, 2, and 3) and arrayed in the order of (i 1). 3 +j, and the input terminals are represented by E ,-(i=1, 2 and 3) and E winding is inserted between the ground and the junction G, of the secondary windings L L and L so that a voltage equal to V /2 is always induced across the secondary winding. Then, the selected output voltage becomes +3/2 V the spurious voltage is /a V or /2 V and the selecting ratio is 1/3.

When the transformer assembly of the type shown in FIG. 7 has input terminals E E E and E E E the number of input terminals is (m n) whereas the number of output terminals is (m n). The output terminals are represented by F (i l, 2, 3, m; k, 1,2,. n), and the input terminals, by E (k l, 2, ,n), E (i=1, 2,. m) and E (i= 1, 2,. ,1). In the winding matrix of the transformer assembly, the elements of the column corresponding to the output terminal P are Is at the rows corresponding to the input terminals E and E whereas the remaining elements are Os. The transformer assembly based upon this winding matrix has (I m n) input terminals and (l m n output terminals.

Seventh Embodiment The seventh embodiment is an improvement of the sixth embodiment so that the voltage difference between the adjacent output terminals of the transformer assembly may be minimized. The winding matrix shown in Table 7 is improved as shown in Table 8.

l O O l (1 0 Table 8 (i= 1, 2 and 3). In the column F,-,-, the elements in the rows corresponding to the input terminals E and E (where x is given from the relation x-l-i-j 1 (mod 3)) are ls whereas the elements in the remaining rows are 05. In like manner, the winding matrix shown in Table 8 is formed by putting x =j when i is an odd number and putting x 4 j when i is an even number. When itakes on the value of l, 2, ,l and j, on the value of l, 2,. m, the number of input terminals is (1+ m) and the number of output terminals, (l m). When the output terminals are represented by F (i l, 2, ,l-,-j= 1,2,...,m;k=l,2,...,n).andarrayed in the order of((i l) 'm+(j 1))x-m 'k. The input terminals are represented by B (k 1,2,. n), E 1, 2, .,m) and E (i= 1, 2, ,1). The elements of the column F in the rows corresponding to the input terminals E E and E are ls whereas the elements in the other rows are Os, where x =j when iis an odd number, x =m +1 j when iis an even number, y k when (i 1) 'l+j is an odd number whereas y=n+ l -kwhen (il)'m+jis an even number.

Alternatively, x and y may be derived from x+ij a n (mod. m), and y+(i l)'m+jl l E k(mod.n)

where h, h are constant integers. Therefore, the number of input terminals is (1-1- m n) and the number of output terminals, (l m n). The signal distance between the adjacent columns is minimum.

Eighth Embodiment Next referring to FIG. 8 the eighth embodiment of a transformer assembly in accordance with the present invention will be described. The transformer assembly is constructed based upon a fixed weight error correct- The winding matrix shown in Table 8 is obtained by ing code derived fromp element code (where p 2, 3, One example, quaternary code, shown in Table 10 will be described. Since the corresponding elements of the columns differ in more than two rows, the minimum distance of this code is 2.

9 10 ll 12 13 14 15 l a 0 1 2 3 1 2 3 0 2 3 0 1 3 0 1 2 a 0 1 2 3 0 1 2 3 0 1 2 3 0 1 2 3] 11,, 0 0 o 0 1 1 1 1 2 2 2 2 3 3 3 3 Table I0 

1. An electrostatic recording apparatus comprising a transformer assembly comprising a plurality of cores equal in number to a length of code words of a predetermined error correcting code, a plurality of primary windings wound on said plurality of cores, respectively, and a plurality of selecting lines the number of which is equal to the number of the code words of said error correcting code at most and each of which comprises a plurality of seriesconnected secondary windings wound on said cores, respectively, in accordance with the elements of each of the code words of said error correcting code; means for energizing said plurality of primary windings with a set of energizing current for selecting a desired one of said selecting lines, each current that composes said set of energizing currents corresponding to each of the elements of the code word associated with said desired selecting line so that the secondary voltages of a predetermined magnitude may be induced across said secondary windings, thereby inducing a selected output voltage across said selected selecting line while inducing across the remaining selecting lines spurious output voltages, respectively, which are lower than said selected output voltage by a magnitude in proportion to a distance between the code word associated with said selected line and each code word associated with each remaining selecting lines; means for generating a set of signals in response to the input information so that the generated set of signals may be amplified to produce said set of energizing currents which may be applied to said primary windings of said transformer assembly to induce said selected output voltage across said selected selecting line; and means for forming electrostatic images, impressing said selected output voltage upon a plurality of electrodes connected to said selecting lines, on a recording medium located in contact with said electrodes, the magnitude of said selected output voltage being so chosen that the input information may be recorded upon said electrostatic recording medium by the discharge between said medium and said selected electrode upon which is impressed said selected output voltage while said spurious output voltage may make no recording due to the threshold characteristics of the discharge between said recording medium and the remaining electrodes upon which said spurious output voltages are impressed.
 1. An electrostatic recording apparatus comprising a transformer assembly comprising a plurality of cores equal in number to a length of code words of a predetermined error correcting code, a plurality of primary windings wound on said plurality of cores, respectively, and a plurality of selecting lines the number of which is equal to the number of the code words of said error correcting code at most and each of which comprises a plurality of series-connected secondary windings wound on said cores, respectively, in accordance with the elements of each of the code words of said error correcting code; means for energizing said plurality of primary windings with a set of energizing current for selecting a desired one of said selecting lines, each current that composes said set of energizing currents corresponding to each of the elements of the code word associated with said desired selecting line so that the secondary voltages of a predetermined magnitude may be induced across said secondary windings, thereby inducing a selected output voltage across said selected selecting line while inducing across the remaining selecting lines spurious output voltages, respectively, which are lower than said selected output voltage by a magnitude in proportion to a distance between the code word associated with said selected line and each code word associated with each remaining selecting lines; means for generating a set of signals in response to the input information so that the generated set of signals may be amplified to produce said set of energizing currents which may be applied to said primary windings of said transformer assembly to induce said selected output voltage across said selected selecting line; and means for forming electrostatic images, impressing said selected output voltage upon a plurality of electrodes connected to said selecting lines, on a recording medium located in contact with said electrodes, the magnitude of said selected output voltage being so chosen that the input information may be recorded upon said electrostatic recording medium by the discharge between said medium and said selected electrode upon which is impressed said selected output voltage while said spurious output voltage may make no recording due to the threshold characteristics of the discharge between said recording medium and the remaining electrodes upon which said spurious output voltages are impressed.
 2. An electrostatic recording apparatus as defined in claim 1 wherein said transformer assembly comprises a plurality of cores equal in number to a length of the code words of a predetermined (n, k) error correcting code, where n denotes the length of the code words and k, an integer not larger than n, a plurality of primary windings, each being wound on each of said n cores, and a plurality of selecting lines the number of which is equal to 2k at most and each of which comprises a plurality of secondary windings connected in series equal in number to the length of said code words n and wound on said n cores, respectively, in the directions in accordance with each element of each code word of said (n, k) error correcting code; said means for energizing said primary windings energizes each primary winding with the respective driving currents, whose polarity is depending upon each element of a selected code word of said (n, k) error correcting code so that the secondary voltages of the polarities dependent upon the polarity of said driving current and the direction of said secondary winding coupled to said primary winding may be induced, the secondary voltages of one polarity being induced across the n secondary windings of the selected selecting line associated with said selected code word of said (n, k) error correcting code so that the n secondary voltages may add up to the selected output voltage on said selected Selecting line, the spurious output voltage induced across each of the remaining selecting lines being n-2d secondary voltages which consists of n-d secondary voltages in the one polarity and d secondary voltages of the opposite polarity, where d denotes the distance between said selected code word and the code word associated with each of the remaining selecting line by cancelling partly one another.
 3. An electrostatic recording apparatus as defined in claim 1 wherein said transformer assembly comprises a plurality of cores equal in number to a length of the code words of a predetermined (n, k) error correcting code, where n denotes the length of the code words and k, an integer not larger than n, a plurality of primary windings, every two of which are wound on each of said cores in directions opposite to each other, a plurality of selecting lines the number of which is 2k at most and each of which comprises a plurality of secondary windings connected in series equal in number to the length of said code words n, and wound on said n cores, respectively, in the directions in accordance with each elements of each code word of said (n, k) error correcting code; and said means for energizing primary windings energizes each one of said two primary windings on each of said n cores in accordance with each element of a selected code word of said (n, k) error correcting code so that the secondary voltages of the polarities depending upon the direction of said energized primary windings and the direction of said secondary windings coupled to said primary windings may be induced, the secondary voltages of one polarity being induced across the n secondary windings of the selected selecting line associated with said selected code word of said (n, k) error correcting code so that the n secondary voltages may add up to the selected output voltage on said selected selecting line, the spurious output voltage induced across each of the remaining selecting lines being n-2d secondary voltages which consists of n-d secondary voltages in the one polarity and d secondary voltages of the opposite polarity, where d denotes the distance between said selected code word and the code word associated with each of the remaining selecting line, by cancelling partly one another.
 4. An electrostatic recording apparatus as defined in claim 3 wherein said transformer assembly comprises a plurality of cores equal in number to a length n of the code words of a predetermined Gray code, a plurality of primary windings, a plurality of selecting lines the number of which is 2n at most and each of which comprises a plurality of secondary windings wound on said cores in the directions in accordance with the elements of each code word of said Gray code in which the distance between the adjacent code words is minimum, whereby the number of cores on which the direction of the secondary windings are opposite for any two adjacent selecting lines may be made minimum with the result that the number of secondary voltages of the opposite polarities induced across the adjacent selecting lines may be minimized and that the difference between the output voltages of the adjacent selecting lines may be minimized to be 2d'' secondary voltages, where d'' denotes the minimum distance.
 5. An electrostatic recording apparatus as defined in claim 3 wherein said transformer assembly comprises a plurality of cores equal in number to a length n of the code words of a predetermined (n, k) error correcting code, when k denotes an integer less than n, a plurality of primary windings; and a plurality of selecting lines the number of which is equal to 2k at most and each of which comprises the secondary windings wound on said n cores, respectively, in the directions in aCcordance with the elements of each code word of said (n, k) error correcting code; the distance between the adjacent code words of said (n, k) error correcting code being minimized using Gray code for the information digits of the code words, whereby the number of cores on which the directions of the secondary windings are opposite for any two adjacent selecting lines may be made minimum with the result that the number of secondary voltages of the opposite polarities induced across the adjacent selecting lines may be minimized and that the difference between the output voltages of the adjacent selecting lines may be minimized to be 2d'' secondary voltages, where d'' denotes the minimum distance.
 6. An electrostatic recording apparatus as defined in claim 1 wherein said transformer assembly comprises a plurality of cores equal in number to a length of the code words of a predetermined fixed weight error correcting code, a plurality of primary windings equal in number to said cores, each of said primary windings being wound on each of said cores, and a plurality of selecting lines each of which comprises a plurality of secondary windings equal in number to the weight w of said fixed weight error correcting code, connected in series, each of said secondary windings being wound on the cores corresponding to the element ''''1'''' of each of said code words consisting of the combination of the elements ''''1'''' and ''''0,'''' the secondary voltages of the same polarity being induced across said secondary windings; and said means for energizing the primary windings energizes w of the primary windings wound on the cores corresponding to the elements ''''1s'''' of the selected code word of said fixed weight error correcting code associated with the selected selecting line so that the secondary voltages may be induced across the secondary windings which are coupled through cores to said w energized primary windings, the secondary voltage being induced across each of the w series-connected secondary windings of said selected selecting line so that the w secondary voltages may add up to the selected output voltage on said selecting line while the spurious output voltage induced across each of the remaining selecting lines being (w-d/2) secondary voltages, where d denotes the distance between said selected code word and the code word associated with each of the remaining selecting lines.
 7. An electrostatic recording apparatus as defined in claim 6 wherein said transformer assembly comprises a plurality of cores equal in number to a length of the code words of a predetermined fixed weight error correcting code in which the distance between the adjacent code words is minimum, a plurality of primary windings, a plurality of selecting lines each of which comprises a plurality of secondary windings wound on said cores, respectively, in accordance with each code word of said fixed error correcting code, whereby the number of the secondary windings of the adjacent selecting lines wound on the same core may become maximum and the difference between the output voltages of the adjacent selecting lines may be d''/2 secondary voltages, where d'' denotes the minimum distance, which is the minimum difference among the output voltages.
 8. An electrostatic recording apparatus as defined in claim 6 wherein said transformer assembly comprises a plurality of cores equal in number to a length of a fixed weight error correcting code derived from a predetermined p-element error correcting code, where p denotes a positive integer larger than one, the code words of said fixed weight error correcting code being equal in number to those of said p-element error correcting code and the length of said fixed weight error correcting code being m X p where m denotes the length of said p-element errOr correcting code, said cores being arranged as to consist of m groups of p cores; a plurality of primary windings, each being wound on each of said cores, and a plurality of selecting lines equal in number to the number of the code words of said fixed error correcting code and each of which comprises a plurality of secondary windings connected in series and equal in number to m the number of said groups of cores, each of said secondary windings being wound on said cores in accordance with said fixed weight error correcting code in such a way that the ith (where i 1, 2, 3, . . . , and m) secondary winding of said selecting line is wound on the hth core in the i-th group of cores, where h denotes the ith element of the code word of said p-element error correcting code corresponding to said selecting line; and said means for energizing the primary windings with a set of driving currents for selecting one of said selecting lines, energizes each selected one of said primary windings in each of m groups corresponding to each of the m elements of the code word of said p-element error correcting code associated with said selected selecting line, so that the secondary voltages may be induced across the secondary windings coupled to said m selected primary windings, the secondary voltage being induced across each of the m series-connected secondary windings of said selected selecting line so that the m secondary voltages may add up to selected output voltage on said selecting line while the spurious output voltage induced across each of the remaining selecting lines being (m-d/2) secondary voltages, where d denotes the distance between the code words of said fixed weight error correcting code associated with said selected selecting line and associated with each of the remaining selecting lines.
 9. An electrostatic recording apparatus as defined in claim 8, wherein said transformer assembly comprises a plurality of cores equal in number to a length of a fixed weight error correcting code derived from a predetermined p-element error correcting code in which the distance between the adjacent code words is minimum a plurality of primary windings, and a plurality of selecting lines, each of which comprises a plurality of secondary windings wound on said cores, respectively, in accordance with each code word of said fixed weight error correcting code, whereby the number of the secondary windings of the adjacent selecting lines wound on the same core may be made maximum and the difference between the output voltages of the adjacent selecting lines, may be d''/2 secondary voltages, where d'' denotes the minimum distance, which is the minimum difference among the output voltages.
 10. An electrostatic recording apparatus comprising a transformer assembly comprising a plurality of cores the number of which is denoted as m, a plurality of primary windings, equal in number to said cores, wound on said m cores, respectively, a plurality of intermediate terminals the number of which is denoted as n, and a plurality of selecting lines the number of which is m X n and each of which comprises one of a plurality of secondary windings each n of which are wound on one of said m cores, one end of the n secondary windings wound on one common core being connected to different one of said n intermediate terminals, respectively, means for impressing voltage upon said intermediate terminals in response to a set of selecting signals, means for energizing said primary windings of said transformer assembly with a set of current in response to said set of selecting signals, thereby inducing the secondary voltages across the secondary windings coupled through the cores to each of said energized primary windings, so that the selected output voltage cOnsisting of the sum of the voltage impressed on said intermediate terminals and said secondary voltages induced across the secondary windings may be impressed across selected selecting lines which are conducted to the intermediate terminals impressed by said voltage and have the secondary windings that are coupled to said energized primary windings and that the spurious output voltage equal in magnitude to the voltage impressed on intermediate terminals may be impressed to the remaining selecting lines connected to said intermediate terminals impressed by said voltage while the spurious output voltage equal in magnitude to said secondary voltages may be impressed to the remaining selecting lines coupled to said energized primary windings, said both spurious voltages being lower than said selected output voltage, means for forming electrostatic images, impressing said selected output voltage upon a plurality of electrodes connected to said selecting lines on a recording medium located in contact with said electrodes the magnitude of said selected output voltage being so chosen that the recording may be made by the electrodes upon which said selected output voltages are impressed while not recording may be made by the electrodes upon which said spurious outputs are impressed because of the threshold characteristics of the discharge between said electrodes and said recording medium, means for storing input information signals, generating, in response to said information signals, said set of signals to select desired selecting lines in timing desired so that the recording of the input information may be made at one time for the electrodes connected to the selecting lines, across all of which one of an intermediate terminal voltage and a secondary voltage induced by an energized primary winding is impressed commonly, on said medium.
 11. An electrostatic recording apparatus as defined in claim 10 wherein said means for impressing voltage upon said intermediate terminals comprises a second transformer assembly comprising a plurality of cores equal in number to a length of code words of a predetermined error correcting code, a plurality of primary windings each wound on each of said plurality of cores, and a plurality of selecting lines equal in number to said n intermediate terminals, each of said plurality of selecting lines comprising a plurality of series-connected secondary windings wound on said cores, respepctively, in accordance with the elements of each of the code words of said error correcting code, one end of each of said plurality of selecting lines being connected to each of said intermediate terminals, respectively, while the other end is connected to a common junction; and means for energizing said plurality of primary windings with a set of energizing currents in response to said set of selecting signals.
 12. An electrostatic recording apparatus as defined in claim 10 wherein said means for impressing voltage upon said intermediate terminals comprises a transformer assembly comprising a plurality of cores equal in number to said intermediate terminals n, a plurality of primary windings wound on said n cores, respectively, and a plurality of secondary windings wound on said n cores, respectively, one end of said secondary windings being connected to said intermediate terminal, respectively, the other ends being connected to a common junction; and means for energizing one of said primary windings in response to said set of selecting signals.
 13. An electrostatic recording apparatus as defined in claim 10 wherein said secondary windings of said transformer assembly connected to the adjacent electrodes and connected to adjacent intermediate terminals are wound on the same core, so that the difference between the output voltages of the adjacent electrodes may become minimum which is equal to the voltage impressed upon the intermediate terminals at the most.
 14. An electrostatic recordiNg apparatus as defined in claim 13 wherein the jth selecting line (j 1, 2, . . . , m) of the selecting lines connected to the odd-numbered intermediate terminals has one of the secondary windings wound on the jth core in said transformer assembly, and, the jth selecting line (j 1, 2, . . . , m) of the selecting lines connected to the evennumbered intermediate terminals has one of the secondary windings on the (m - j + 1)th core in said transformer assembly.
 15. An electrostatic recording apparatus as defined in claim 13 wherein the j-selecting line (j 1 through m) of selecting lines connected to the ith intermediate terminal (i 1 through n) has one of the secondary windings on the xth core in said transformer assembly, where x is given by x + i + j k (modulo m) where k is a constant integer.
 16. An electrostatic recording apparatus as defined in claim 10 wherein said n secondary windings connected to said n intermediate terminals in each of said m cores are arranged in accordance with predetermined m arrays of n digits which are so arranged that the chance that a pair of digits come into the adjacent position in said m arrays is not larger by one than the mean number of the chance that a pair of digits come into the adjacent position in said m arrays for all the combinations nC2 of pairs of n digits, whereby the change that the secondary windings connected to a pair of said intermediate terminals come to the adjacent position on the same core may be equalized with the result that the maximum stray capacitance between a pair of said intermediate terminals may be reduced.
 17. An electrostatic recording apparatus as defined in claim 16 wherein said secondary windings are wound in a plurality of layers. 